pro-sentence

A pro-sentence is a function word or expression that substitutes for a whole sentence whose content is recoverable from the context. Pro-sentences are a kind of pro-forms and are therefore anaphoric.In English, yes, no, okay and amen are common pro-sentences. In response to the question "Does Mars have two moons?", the sentence "Yes" can be understood to abbreviate "Mars has two moons."Pro-sentences are sometimes seen as grammatical interjections, since they are capable of very limited syntactical relations. But they can also be classified as a distinct part of speech, given that (other) interjections have meanings of their own and are often described as expressions of feelings or emotions.
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